Spark plug



Jan. 25, 1938., OYD 2,106,449

SPARK PLUG Original Filed Sept. 12, 1954 Patented Jan. 25, 1938 UNITED STATES PATENT OFFICE r SPARK PLUG Charles E. Boyd, Chicago, Ill.

Application September 12, 1934, Serial No. 743,669 Renewed March 5, 1937 4 Claim.

vide a spark plug in which the ground electrode is positioned diametrically of the plug and will act to split and deflect the oil to prevent clogging and fouling of the spark gap by the oil.

following description taken in connection with the attached drawing, in which Figure 1 is a side elevation of my improved plug and showing in section a portion of the cylinder wall in which the spark plug is mounted;

Figure 2 is a side elevation of the spark plug, the view being taken at right angles to that of Figure 1;

Figure 3 is a vertical section taken on the plane indicated 33 in Figure 2;

Figure 4 is a plan view of the lower end of the p Figure 5 is a side elevation of a modified form of the plug, and

Figure 6 is a plan view the plug shown in Figure 5.

The spark plug in the usual manner includes a metallic shell l0 having a threaded portion 12 whereby the plug may be threaded into the cylinas illustrated in Figure 1. The head of the shell 10 is formedwith a nut portion [6 for threading the plug into the wall I4 and a of the bottom end of apparent that since the electrode 40 gasket l8 may be used for sealing the joint between the shell IO and the wall I.

The shell I0 is tubular in form and is adapted to receive an insulator 20,'which is intended to be an additional gasket 30 above the shouldered portion 26 of the insulator. An electrode 32 extends axially through vthe insulator 20 and the outer extremity 34 of the electrode is provided with a 1 terminal connector 36. The inner'extremity 38 of the electrode 32 protrudes for a short distance beyond the tip 22 of the insulator; I j

I provide a ground electrode 40 positioned diametrically with respect to the shell l0 and fixedly .20

secured at its ends to the shell I0. It'will be isrlgidly position, that it isnot subject to defiection by the heat andtherefore the spark gap between the ground electrode electrode 38 remains vented from fouling the spark gap.

of the best grade of refractory and having a f;

40 and thecentral 2s The lateral openings 42 provide vent openings for the spark gap and also form a ring-shaped portion 44. This relatively thin metal ring may also be formed by a plurality of openings such as shown in Figure 5 to be presently described, wherein the ring is supported from the body of the shell by several narrow portions. The ring readily heats up during use of the plug and therefore burns off any oil or other matter deposited thereon. The ground electrode associated with the ring portion is also maintained at a relatively high temperature and thus is self-cleaning. self-cleaning feature is also present in the center electrode which is covered and protected by the insulator 22 except for the lower tip 33. This tip therefore readily heats up and likewise burns off the oil that may be deposited thereon.

Although I have shown in Figures 1 to 4. a preferred design of my plug, it will be obvious that other forms may be resorted to without departing from the spirit of my invention and the venting openings may be formed in different manners. For example, I have shown one modified construction in Figures 5 and 6 in which the spark plug construction is substantially as that disclosed in Figures 1 to 4 except that the shell l9,

, instead of being formed with notched openings, is

provided with a plurality of radial holes 553. In both forms it will be apparent that the venting openings are laterally disposed with respect to the spark gap and it should also be noted that the lower or inner end of the insulator 2i] terminates in a horizontal plane with or preferably above the inner and upper edges of the venting openings in order to prevent fouling of the insulator and burning of the electrode. It has been found by test that spark plugs as disclosed herein will have a' longer life withoutfailure than other plugs now on the market when used under similar conditions and it is believed that the improvements in operation are due to the novel arrangement and cooperation between the ground electrade and the venting openings.

Various changes and modifications may be resorted to in the practice of my invention without departing from the spirit of my invention as expressed in the appended claims.

I claim:

l.'A spark plug comprising a metallic shell adapted to be threaded into a cylinder wall, a ground electrode diametrically positioned with respect to said shell and fixedly secured at its ends to the lower end of said shell, an insulating electrode-retaining body positioned centrally within said shell and removably secured thereto to provide an axial spark gap, said shell having notched openings formed therein adjacent the lower end thereof and above said ground electrode, said notched openings being so formed as to leave a This substantially thin ring-shaped portion at the lower end of said shell and said openings being laterally disposed with respect to the axial spark gap between the electrodes.

2. A spark plug comprising a substantially tubular metallic shell adapted to be threaded into a cylinder wall, a notched vent opening formed in the lower end of said shell below the threaded portion thereof by a substantially horizontal cut and an angular cut, a ground electrode diametrically positioned with respect to the lower end of said shell and fixedly secured to said shell immediately beneath said notched opening, an insulator centrally positioned within said shell and removably secured thereto, the lower end of said insulator terminating substantially adjacent the upper edge of said notched opening and an electrode carried by said insulator and axially projecting from the lower end thereof to provide an axial spark gap with respect to said ground electrode, whereby said vent opening is laterally disposed with respect to said spark gap.

3. A spark plug comprising a substantially tubular metallic shell having an external thread thereon whereby said shell may be threaded into a cylinder wall, the lower end of said shell beneath said external thread having a pair of notched openings cut therein through a large area thereof and defining at the lower end of said shell a substantially thin ring-like portion supported from the body of said shell by relatively narrow uncut portions, a ground electrode diametrically positioned with respect to said ringlike portion and fixedly secured at its ends thereto, an insulator centrally positioned with respect to said shell and removably secured thereto, a central electrode carried by said insulator and projecting from the lower end thereof to leave a substantially axial spark gap between said electrodes whereby oil is deflected from said spark gap by said ground electrode and vented through said opening to prevent fouling of the plug.

4. A spark plug comprising a metallic shell, an insulator centrally positioned within said shell, an electrode fixedly secured to the lower end of said shell, an axially disposed electrode carried by said insulator and projecting from the lower end adjacent to said ground electrode to leave a spark gap, said shell having a plurality of notched openings formed therein above said ground electrode and disposed substantially laterally with respect to the spark gap, said notched openings having a size and being arranged so as to leave a substantially thin ring-shaped portion at the lower end of said shell, whereby said relatively thin ring portion will heat up readily and burn ofi any oil that may be deposited on the ring or on the ground electrode having association therewith.

' CHARLES R. BOYD. 

